You are about to say goodbye to the world of SDTVs, or standard definition televisions, and welcome HDTVs or high definition televisions. One of the first things that would differentiate each is the capability for most of HDTVs to have a progressive scan output. Progressive scan is basically the ability to display each line of each frame all at once.
As a simple illustration, imagine a picture is composed of 10 lines. Those ten lines display different colors found in the picture. If the picture moves, then the lines will have to display different colors. For SDTVs only 5 of those lines change display, while the other alternating 5 lines change display after the first batch has changed display. For progressive scan, all ten lines change display at the same time. You may say that it isn't really important just as long as you see the picture. Well, yes, you can see the picture, but it comes out a bit blurry especially with motion sequences. Here's a picture to show you the difference between both.
You notice that the picture on the left is more blurry, and that there are lines on the bottom area. This is what happens on SDTVs. TV sets that are capable of progressive scan display can display frames with sudden movements better. All lines change image at the same time, compared to interlaced display, where the lines that change are alternating, so the other lines are left with older frames. I'll be getting into more detail in the next few entries since the topic on HDTVs are a lot more complicated than just progressive scan.
picture: apple.com
